1. Field of the Invention
The present invention relates generally to detecting subterranean hydrocarbon accumulations, and more particularly, but not by way of limitation, to detecting such accumulations by introducing gases therein which explode in the presence of hydrocarbons.
2. Description of the Prior Art
Seismic geophysical exploration has been practiced for many years to determine the configuration of subterranean formations and the possible favorable structural or stratographic traps for the accumulation of hydrocarbons. Such processes generally involve the detonation of explosives on the earth's surface or forcibly contacting the earth's surface with a reciprocating mass whereby seismic waves are generated which travel through the earth and reflect from subterranean formations back to a plurality of geophones or seismometers on the earth's surface. The geophones or seismometers in combination with other seismographic equipment produce electric waves which are processed and recorded in a manner permitting determination of the depth and dip of the seismic wave reflecting horizons.
In other similar seismic exploration processes, explosive materials are placed beneath the surface of the earth and detonated in order to generate seismic waves therein. For example, U.S. Pat. No. 3,702,635 issued Nov. 14, 1972 to Farr discloses seismic exploration in soft areas, such as marshes, swamps, water or other unstable terrain wherein a liquid explosive is placed beneath the surface and remotely detonated to produce seismic waves therein. U.S. Pat. No. 2,353,484 issued on July 11, 1944 to Merten et al. discloses the use of explosive gas mixtures, e.g., acetylene and oxygen, in geophysical exploration wherein the gas mixture is forced into a subterranean cavity or formation and then detonated to generate seismic waves in the earth. Examples of other patents which disclose seismic exploration processes wherein explosive gases are injected beneath the surface of the earth and then detonated by mechanical means such as spark ignitors to generate seismic waves are U.S. Pat. No. 4,026,382 issued May 31, 1977 to Field et al. and U.S. Pat. No. 3,752,256 issued Aug. 14, 1973 to Mollere.
By the present invention methods are provided for detecting the presence of hydrocarbon accumulations in subterranean formations penetrated by well bores and simultaneously generating seismic waves from within the formations which travel through the earth and which are detected using known seismographic apparatus to determine the extent of the formations containing the hydrocarbon accumulations. In addition, in formations containing liquid hydrocarbon accumulations, the methods of the present invention can be utilized to determine the locations of the upper and lower extremities of the accumulations.